1. Field of the Invention
The present invention generally relates to an image forming apparatus and method for forming images on paper and an image forming system, and more particularly, to processing of compressed image data.
2. Description of the Related Art
In general, an image forming apparatus of this type is designed to internally process compressed image data transferred from a host computer that serves as a host device, and then output the image data to a printer engine. Various formats have been suggested and put into practice for compressed image data transferred from a host computer to an image forming apparatus. For example, Japanese Unexamined Patent Publication No. 11-98343 discloses a technique of outputting fixed-length compressed RGB image data from a host computer to a printer. In a case where each color data of RGB is 8-bit long, 384-bit bitmap image data of 4×4 pixels are constantly compressed to data of a fixed length of 64 bits.
However, as fixed-length compressed image data are transferred from a host computer to a printer, it takes the printer a long period of time to receive and process the compressed image data. Also, there is a problem of requiring a large-capacity memory for storing fixed-length compressed image data inside the printer.